This invention relates to compositions and methods for use during the rinse cycle of home laundering operations. The compositions are especially effective for providing crispness and soil release benefits to fabrics.
Modern fabric conditioning compositions, washing machines and dryers are subject to continuous improvement with a view to achieve a series of fabric benefits such as, for example, softening, body, anti-wrinkling, ease of ironing, and improvement in appearance.
One prevalent laundry attribute that consumers desire is that fabrics maintain their original crisp look and feel, particularly those items which are routinely ironed. Accordingly, it is an object of the present invention to provide a rinse-added fabric conditioning composition which impart crispness to fabrics rinsed therein. It has now been found that the above objective is met by a rinse-added fabric conditioning composition containing starch. According to the present invention, the starch added in the rinse deposits uniformly on the fabric. This starch can then impart crispness to the fabric, particularly after exposure to heat (e.g., steam ironing, tumble drying).
It has also been found that the starching film provides resistance of the fabric to subsequent soiling and allows subsequent soils to be more easily removed. The removal in the subsequent wash can be done by chemical means (e.g., hydrolysis, amylase digestion) or physical mean (e.g., solvation, simple physical desorption and separation from, the fabric).
Detergent compositions comprising starch are not new per se. Example is U.S. Pat. No. 3,892,681 describing substantially water-insoluble starch. The starch is characterised by a granular diameter of 0.1-45 microns and a swelling power of less than 15 at 65xc2x0 C. improves the softness, the ease of ironing, the anti-static and anti-wrinkling performances. As of yet, however, no single fabric conditioning composition is available capable of providing textiles treated therewith in the conventional matter with the fabric-care benefits as referred to hereinabove.
The present invention provides rinse-added fabric conditioning compositions which are capable of imparting crispness and soil release benefits to the fabrics. These compositions comprise a specific starch having a gelatinization temperature of less than 150xc2x0 C. In a preferred embodiment, the compositions further contain, in addition to the specific starch, a perfume.
In its method aspect, the present invention relates to a method for treating fabrics to simultaneously impart crispness and improved subsequent cleaning benefits.
The rinse-added fabric conditioning compositions of the present invention comprise as an essential element a specific starch having a gelatinization temperature of less than 15020  C. The gelatinization temperature for gelatin is determined as setting point, several methods have been used to determine the setting point. Example is F. W. Wainwright, GGRA bull. 17(3), 10 (1966).
Although the final choice of starch which will meet requirements of this invention depends upon the origin of the material and also upon process conditions such as bleaching, degradation, and isolation applied to a given species, suitable starches can for example be selected from
a. naturally occuring (e.g., corn, wheat, rice, tapioca, potatoes) or physically modified (e.g. small particle size such as rice starch or milled to promote smaller particle size and low temperature gelling; highly branched amylopectin content such as xe2x80x9cwaxyxe2x80x9d starch grades; pre-gelatinized; acid treated).
b. chemically modified (e.g. hydroyxalkyl substituted ethers, tertiary and quaternary aminoalkyl starch phosphates, starch acetates).
Preferred starches are starch compounds that are easy to formulate into a solid or liquid product; readily disperse in the final rinse; can be co-delivered with other ingredients such as perfumes; do not promote any adverse effects on fabrics (e.g. yellowing); and are readily strippable in the following wash.
Examples of preferred soluble modified and/or natural starches are waxy starches with PO (hydroxy propyl) groups, quaternary amine groups, a combination of PO and quats, high molecular cross linked and modified starches. Commercially available starch derivatives of this class are: Gelex(copyright), Polar gel(copyright) from American maize, Sta-lok(copyright) 180 and 374, Star-pol(copyright) 480 and 560 from Staley starch, Thermoflo(copyright), National 1658 and Firm-tex from National starch.
The above mentioned benefit of crispness are obtained by the swelling and solvation of starch compounds at high temperature (50-75xc2x0 C.), gelatinization. These mechanisms result in the forming of a hydrophilic film that binds to the cellulose fibers of the fabric. The hydrophilic film retains the hydrophilic character of the fabric and the water vapor perneability.
The benefit of improved soil release removal is a result of the hydrophilic film serving as a protective soil release barrier (e.g., soil repellant, soil absorbent or adsorbent, surface modifier to aid detergency, etc.). During a subsequent wash, these films would be at least partially removed by detergents.
The starch can be added in the rinse as a dry powder or can be formulated and admixed as a cold water dispersion.